Applicants' invention relates generally to IP based networks and, more particularly, to mobility between IP based networks.
Fixed data networks, such as the Internet, have conventionally been used for the communication of digital data between different nodes in the network. With the increasing use of mobile nodes, however, such as portable notebook computers, fixed data networks have often become disadvantageous due to the lack of connections to the fixed data network at any specific location to which a mobile node might roam. To solve this problem, data communications using mobile communications system have been implemented to provide mobility for mobile nodes. Such mobile data communications systems typically involve packet radio systems such as General Packet Radio Services (GPRS) or Cellular Digital Packet Data (CDPD) that use IP based protocols. These packet radio systems advantageously permit a mobile node to roam within a cellular network while retaining the ability to initiate data communications at any location within the network.
Mobility in data communications is, however, problematic when a mobile node moves across cellular networks. Thus, if a mobile node moves from a first network to a second network data communications may be lost. For example, in a GPRS system, interGGSN (Gateway GPRS Serving Node) communication is currently not defined and, thus, data packets will be lost because a tunnel cannot be established to reroute data packets to the new Serving GPRS Serving Node (SGSN) in the second network from the old SGSN/GGSN in the first network. Seamless data communication with a mobile node, when the mobile node roams between two heterogeneous packet data networks, thus cannot be achieved using current IP based protocols.